[Radiance-general] Radiance, objline, objpict etc..

[Thomas Bleicher]

On 24 Jan 2008, at 00:33, steve michel wrote:

>
> I was running test renders to determine some electric lighting
> levels at a back wall: I had run ies2rad for the fixtures and
> associated the distribution to simple flat geometry

ies2rad does that for you. You don't have to add 'geometry'
to make the light appear.

> to the same plane as the ceiling.

Bad move. Try to keep at least a tiny distance to the ceiling.
Actually, ies2rad creates the light sources a few mm below the
origin of the light distribution. If you place your fixture
scene file (the .rad file that's created by ies2rad) at 2.5m
the disc or rectangle will be at 2.4975m; enough for Radiance
to keep light source and ceiling apart.

> When I render I don't 'see' the lights

Did you use the -i option for ies2rad? This would use an 'illum'
type for the source which is invisible in a picture. The default
light source should be visible, though.

Do you miss the bright light source itself or is there no light
at all in your scene?

> so I ran objline and
> objpict to check that the geometry of fixtures are there
> and get the following errors:
>
> $ objline Scene_1.rad | x11meta
> fatal - cannot open file "/usr/local/lib/ray/meta/vchars.mta", mode  
> "r"

quick guess: this path is hardcoded in one of the scripts that are used
by objline or x11meta. I think these tools are fairly uncommon these  
days
when everyone just fires up rvu to get a preview.

> $ objpict Scene_1.rad | ximage
> oconv: system - cannot open scene file "/usr/local/lib/ray/lib/ 
> testroom": No such file or directory

On my system I have '/usr/local/lib/ray/lib' hardcoded in the
script 'objpict'. I use the /usr/local/ prefix so I can not say
if it's adjusted by the installer or not. Your error suggests it's
not so you could adjust the script yourself. The path is defined
in the first line after the comments.

> 2-Could someone clarify the visibility of lighting distributions
> in  radiance.

Typically light sources from IES files are visible, as disc,
rectangle or box. You can use the '-i' option to allow a fancy
fitting geometry to appear and still have the light distribution
for the room. Also, the '-dv' option in rpict switches off the
rendering of sources as bright objects (they will appear black).

Hth,
Thomas